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195 Cards in this Set
- Front
- Back
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What are isotopes? |
Atoms of the same element with different numbers of neutrons
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What are the 3 isotopes of Hydrogen? |
Hydrogen, Deuterium, Tritium |
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An atom is about 10^-10m in diameter. How many would fit across a pinhead 0.1mm wide? |
10^6 (one million) |
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What is the formula of a nitrite ion? |
NO2 - |
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What is the formula of a nitrate ion? |
NO3- |
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What is the formula of a phosphate ion? |
PO4 3- |
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What is referred to by the Ar of an element? |
The weighted mean mass of an atom compared with one twelfth of the mass of carbon-12 |
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What is meant by 'relative molecular mass'? |
The mass of a compound made out of molecules relative to one twelfth an atom of carbon 12 |
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What is meant by 'relative formula mass'? |
The mass of an ionic compound relative to one twelfth an atom of carbon 12 |
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What is meant by 'relative isotopic mass'? |
The mass of an isotope relative to one twelfth the mass of an atom of carbon 12 |
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In a mass spectrometer, how is it that the detector can record at what point every particle is deflected? |
A variable magnetic field ensures that all ionised particles deflected into the detector (at different strength). |
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In a mass spectrum, what does m/z represent? |
The mass to charge ratio of each substance; the relative mass of it if only 1+ charged ions are considered |
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What is meant by the term 'molecular formula'? |
Formula that displays the number of atoms of each element in a molecule |
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What is meant by the term 'empirical formula'? |
The simplest whole number ratio of atoms of each element in a compound |
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Many coloured salts are hydrated, and have water molecules as part of their crystal structure. What are they referred to as when this excess water is evaporated off? |
Anhydrous |
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What is percentage error? |
The margin of error that is present when using apparatus (a measure of how precise a piece of apparatus gives a value compared to its true value) |
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How do you calculate percentage error? |
maximum error (usually half a graduation) -------------------------------------------------- x100 actual value |
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When is a pipette required in an experiment? |
When a small, fixed volume of liquid or solution is required |
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When is a burette required in an experiment? |
When in need of variable volumes of solution or liquid |
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When is a volumetric flask required? |
When a larger volume of liquid or solution is required |
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What is meant by the term 'standard solution'? |
A solution with a precisely known concentration |
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What problems could you encounter when handling substances for use in an experiment? |
Unwanted reactions could occur (e.g. with the carbon dioxide and oxygen in the air) and impure substances (e.g. damp solids that still contain moisture) could affect recorded mass. |
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What problems could you encounter in heating a substance until it decomposes? |
It may be unclear as to when the decomposition is complete, or as to whether further decomposition has occurred |
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What problems could you encounter when collecting gas in an experiment? |
Some gas may have escaped, or if gas is collected over water, may have dissolved |
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What problem could you encounter in enthalpy experiments? |
Heat loss |
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What is the relative mass of an electron? |
1/1836 |
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What is a molecular ion peak? |
The peak corresponding to the relative molecular mass of the compound |
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What name is given to parts of compounds in an equation that do not participate within the reaction? |
Spectator ions |
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What is the concentration of a solution measured in? |
mol dm^-3 |
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What is an acid? |
A species of proton (H^+ ion) donors that have pH values of lower than 7 when in aqueous form |
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Why are some acids (e.g. ethanoic acid) weaker than others? |
They only partially disassociate in water |
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What is a base? |
A species of proton (H^+ ion) receivers that have pH value of above 7 in aqueous form |
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Why is ammonia a weak base? |
Only a small proportion of its gas NH3 will react with water |
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What practical applications do bases have in everyday life? |
MgO is suspended in water to form milk of magnesia, which is used to treat indigestion Ca(OH)2, i.e. calcium hydroxide, is used to treat acidic soils |
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What is an alkali? |
A certain type of base that dissolves in water to give hydroxide (OH^-) ions |
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What is the term for a reaction where protons and hydroxide ions meet and form water? |
Neutralisation reaction |
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What is meant by the term 'oxidation number'? |
The number assigned to an atom or ion to describe its state of oxidation or reduction. It indicates how many electrons have been gained or lost when bonds have formed. |
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What is the oxidation number of H in H2? |
0 |
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How does a given charge (on an element or on a polyatomic ion) affect oxidation number? |
- in simple ions, the element's oxidation state will be the charge on the ion - in polyatomic ions, the sum of the oxidation states of the elements within the complex ion must total the charge on the ion |
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When does oxygen not have an oxidation state of -2? |
When it is in a peroxide, at which point it has oxidation number -1 |
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When does hydrogen not have an oxidation state of +1? |
In metal hydrides, where it has oxidation state -1 |
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When does chlorine not have an oxidation state of -1? |
In compounds with oxygen and fluorine, at which point its oxidation number can vary |
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What is oxidation? |
Oxidation can be described in 4 ways: - [the addition of oxygen] - [the removal of hydrogen] - the loss of electrons - the increase of oxidation number |
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What is reduction? |
Reduction can be describe in 4 ways: - [the removal of oxygen] - [the addition of hydrogen] - the gain of electrons - the decrease of oxidation number |
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What is an oxidising agent? |
A species that causes another element to increase in oxidation number; it is itself reduced |
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What is a reducing agent? |
A species that causes another element to be reduced; it is itself oxidised |
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What does the number of a period indicate about the elements within it? |
The number of the highest energy electron shell that the elements in that particular period have |
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Is an ionisation reaction endothermic or exothermic? |
Endothermic |
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What is the first ionisation energy? |
The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions |
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What is activation energy? |
The minimum energy required to start a reaction by breaking bonds |
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What is addition polymerisation? |
The formation of a very long molecular chain by repeated addition reactions of many unsaturated alkene molecules |
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What is an addition reaction? |
A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule |
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What is adsorption? |
The process that occurs when a gas or liquid or solute is held to the surface of a solid |
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Define alicyclic
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As containing carbon atoms in a (non-aromatic) ring |
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Define aliphatic |
As containing carbon atoms joined together in straight or branched chains |
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What is an alkyne? |
A hydrocarbon containing at least on triple carbon-carbon bond |
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Define anhydrous |
Containing no water molecules |
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Define aromatic |
As containing one or more benzene rings |
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What is Avogadro's hypothesis? |
Equal volumes of gases at the same temperature and pressure contain the same number of molecules |
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What is a catalyst? |
A substance that increases the rate of a chemical reaction without being used up in it |
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How does a catalyst increase the rate of a reaction? |
It provides an alternative route for the reaction by providing a surface for the reaction to occur on, or by forming an intermediate complex before being regenerated
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What is cis-trans isomerism? |
A special type of E/Z isomerism where there are two non-hydrogen groups in different positions |
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What is a system isolated from its surroundings called? |
A closed system |
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Define a coordinate/dative covalent bond |
A shared pair of electrons in which the bonded pair has been provided by only one of the bonding atoms |
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What is covalent bonding? |
The strong electrostatic attraction between a shared pair of electrons and the nuclei of bonded atoms |
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What is the process called by which an elimination reaction in which water is removed from a saturated molecule to create an unsaturated molecule? |
Dehydration |
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What is desorption? |
The release of an adsorbed substance from a surface |
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What is a dipole? |
A separation in electrical charge so that each of the ends of a covalent bond have slight opposite charges. |
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What suffix do you apple when a non-metal ion? |
-ide |
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Do mass spectrometers analyse negative ions? |
No - positive ions are the only ions formed in a mass spectrometer |
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How can you differentiate between water and heavy water? |
In solid form, normal ice will float in water while ice made from heavy water sinks |
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What is a binary compound? |
One that contains 2 elements only |
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Define univalent |
As having valency 1 (e.g. Group 1 and Group 17 atoms) |
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Define divalent |
As having valency 2 |
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Define trivalent |
As having valency 3 |
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Define 'mole' |
The amount of a substance that contains Avogadro's constant number of particles (the amount of particles in 12g of Carbon 12) |
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What is Avogadro's constant to 3 s.f.? |
6.02 x10^23 |
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At room temperature, what volume does 1 mole of gas take up? |
24dm^3 |
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What piece of apparatus would you use to reduce red copper oxide to copper? |
A combustion tube |
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What equation would you use to find the number of moles of a solution with known concentration and volume? |
n = cV |
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What is RTP? |
Room-temperature-pressure; 20 degrees Celsius and 101kPa pressure |
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What is the ideal gas equation? |
pV = nRT Where p = pressure (Pa), v = volume (m^3), n = moles of gas (mol), R = ideal gas constant (8.31Jmol^-1K^-1), T = temperature (K) |
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What is the best way to measure gas given off? |
Using a gas syringe |
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Is diluting an acid exothermic or endothermic? |
Exothermic |
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Define the term 'atomic orbital' |
A region around the nucleus of an atom where it is likely to find electrons, specifically a region that can hold 2 electrons with opposite spin |
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Describe the shape of an S orbital |
Spherical |
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Describe the shape of a p orbital |
Dumbbell shaped |
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What is the Aufbau principle? |
The concept that orbitals are filled one electron at a time from the lowest energy level upwards |
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What is Hund's rule? |
Orbitals are filled singly first, then others are added with opposite spin to avoid electron repulsion |
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What is special about Copper and Chromium?
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They are in the d-block but are not transition elements; their 4s orbital is half filled so that their 3d subshell can be half or fully filled to maintain stability |
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Which subshell is normally filled first - 3d or 4s? |
4s |
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Why is the 3d subshell filled after the 4s subshell |
The 4s subshell has a slightly lower quantum energy level |
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What is Avogadro's law? |
That which states: equal volumes of all gases at the same temperature and pressures have equal number of molecules
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How do you find the volume of a liquid if given the mass and density? |
Volume = mass/density |
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In a titration, when close to the endpoint, why do we add the standard solution dropwise? |
To measure the endpoint accurately |
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What colour does methyl orange turn to in acidic conditions? |
Red |
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What colour is methyl orange in alkaline conditions? |
Yellow/orange |
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What colour is Phenolphthalein in acidic conditions? |
Colourless |
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What colour is phenolphthalein in alkaline conditions? |
Pink |
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What colour is Phenol Red in acidic conditions? |
Yellow |
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What colour is Phenol Red in alkaline conditions? |
Pink |
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What is a salt? |
A compound formed by the reaction of a metal/base and an acid, where the metal displaces the hydrogen ion donated by the acid |
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What is formed by the reaction of an acid and a base? |
Salt + water |
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What is formed by the reaction of an acid and an alkali? |
Salt + water |
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What is formed by the reaction of a metal and an acid? |
Salt + hydrogen |
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What is formed by the reaction of an acid and a carbonate? |
Salt + Water + Carbon dioxide |
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What is a dibasic/diprotic acid? |
An acid that has two hydrogen ions to donate |
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Give an example of a dibasic acid |
H2SO4 |
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How do you test for the presence of a carbonate ion? |
Test the compound with a dilute acid, then, if gas is evolved, run the gas through lime water to see if it goes cloudy. |
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How do you test for sulfate ions? |
Add barium chloride or barium nitrate; white precipitate is formed |
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If testing both for sulfate ions and halide ions, would you use barium chloride or barium nitrate in the initial test for sulfate ions? |
Barium nitrate as this wouldn't interfere with the halide test |
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How would you test for halide ions? |
Test the compound with silver nitrate solution; Chloride ions form a white precipitate and this redissolves in dilute ammonia, Bromide ions form a cream precipitate (this redissolves in concentrated ammonia), and Iodide ions form a yellow, ammonia-insoluble precipitate |
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How would you test for ammonium ions? |
Warm the solution with dilute sodium hydroxide. Test the gas evolved with moist red litmus paper; if it turns blue, ammonium ions are present |
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What is the definition of an ionic bond? |
The strong electrostatic attraction between two oppositely charged ions |
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What is the definition of a covalent bond? |
The strong electrostatic attraction between two atoms due to a shared pair of electrons. |
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Define isoelectronic |
As having the same electronic configuration |
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What is a cation? |
A positively charged ion |
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What is an anion? |
A negatively charged ion |
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Describe the structure of giant covalent molecules |
Strong, regularly arranged lattices held by covalent bonds |
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Describe the structure of giant ionic compounds |
Giant lattices with regular arrangement of alternately charged ions |
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What is a dative covalent bond? |
A covalent bond in which both bonding electrons are donated by one of the atoms in a bonding pair |
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By how much does an lone pair of electrons change the angle of certain bonds? |
By -2.5 degrees |
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What shape and bond angles would a molecule with 4 bonding pairs and no lone pairs have? |
Tetrahedral, 109.5 degrees |
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What shape and bond angles would a molecule with 3 bonding pairs and one lone pair have? |
Trigonal pyramidal, 107 degrees |
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What shape and bond angles would a molecule with 2 bonding pairs and 2 lone pairs have? |
Non-linear, 104.5 degrees |
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What is the definition of delocalised electrons? |
Electrons not associated with a single atom or covalent bond. |
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Define electronegativity |
The tendency of an atom to attract a bonding pair of electrons |
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Which is the most electronegative element? |
Fluorine |
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Define intramolecular forces |
Attractive forces within molecules, i.e. covalent bonds |
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Define intermolecular forces |
Attractive forces between molecules, e.g. hydrogen bonding |
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What is a permanent dipole-dipole interaction? |
A type of van der waals force between molecules that contain atoms with significant electronegativity differences (e.g. polar molecules) |
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What is hydrogen bonding? |
A relatively strong form of intermolecular interaction between hydrogen atom/s in one compound and oxygen or fluorine in another. |
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What are induced dipole-dipole interactions (London forces)? |
A type of Van Der Waal's force in which the momentary unequal distribution of electrons in one atom induces that of another and an attraction is temporarily formed (between delta negative and delta positive sides of the atoms) |
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What is periodicity? |
The recurring trends/features across a period. |
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What is meant by the term atomic radius? |
The distance between the nucleus of an atom and its furthest electron |
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What is the trend in ionisation energy down a group? |
It decreases |
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What is the trend in electronegativity across a period? |
Electronegativity increases |
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What is the trend in electronegativity down a group? |
Electronegativity decreases |
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What is the trend in ionisation energy down a group? |
Decreases due to electron shielding |
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Does atomic radius increase or decrease down a group? |
Increase |
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In group two, what is the trend in melting points? |
Generally decreases (magnesium is exception) |
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In group 17, what is the trend in melting/boiling points? |
General increase |
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What is the definition of first ionisation energy? |
The energy required to remove one mole of electrons from one mole of atoms to form one mole of 1+ ions |
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What are the practical uses of group 2 elements? |
Hydroxides such as Calcium hydroxide and Magnesium Hydroxide used in neutralising soils or stomach acid
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Would chlorine displace bromine in solution? |
Yes; chlorine is more reactive bromine. |
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What is the term used to describe a reaction where an element is both reduced and oxidised? (e.g. in the formation of bleach) |
Disproportionation |
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Why is chlorine used in water treatment? |
It is a highly effective disinfectant |
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What is the definition of enthalpy change? |
Delta H is the change in enthalpy that occurs in a reaction |
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What is an endothermic reaction? |
A reaction that absorbs energy |
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What is an exothermic reaction? |
A reaction that transmits energy |
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Define activation energy |
The energy required to give a sufficient amount of molecules sufficient energy for a reaction to occur |
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Define average bond enthalpy |
The average enthalpy change that occurs when breaking 1 mole of a bond in the molecule of a gaseous species under standard conditions |
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What is specific heat capacity? |
The amount of energy needed to heat 1g of a substance by 1 degree celcius |
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Define enthalpy change of neutralisation |
The enthalpy change that occurs when an acid and an alkali react to form one mole of water under standard conditions |
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Define enthalpy change of formation |
The enthalpy change that occurs when one mole of a compound is formed from its constituent elements under standard conditions |
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Define enthalpy change of combustion |
The enthalpy change that occurs when one mole of a compound reacts fully with (completely combusts in) oxygen under standard conditions |
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What is meant by standard conditions? |
101kPa and 25 degrees celcius |
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What is Hess' law? |
The law that regardless of the route taken to the end product of a reaction, the overall enthalpy change will always be the same |
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How would you measure the rate of a reaction from a graph? |
Extrapolate from a tangent line to the graph |
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What is a catalyst? |
A species not used up within a reaction which provides an alternative route for a reaction with a lower activation energy |
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How does increasing the concentration of a reagent affect rate of reaction? |
It increases it |
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How does increasing the surface area of a reagent affect rate of reaction? |
It increases it |
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How does reducing temperature of a reagent affect rate of reaction? |
It decreases it |
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What does the area underneath a Boltzmann distribution show? |
Number of particles reacting |
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What does adsorb mean? |
Temporarily bind to a surface (for correct orientation etc) |
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What is a homogenous catalyst? |
A catalyst in the same state of matter as the reagents in a reaction, or a miscible substance. These form intermediates with the reagents but return to normal form at the end of a reaction |
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What is a heterogenous catalyst? |
A catalyst in a different state of matter than reagents, or an immiscible substance. These provide surfaces for adsorption in a reaction |
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What is dynamic equilibrium? |
The point at which the rates of both the forward and reverse reactions are the same |
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What is Le Chatelier's principle? |
The idea that in reversible reactions, if a condition is changed, the point of equilibrium will shift to accommodate this change |
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Why are practical optimum conditions in ammonia manufacturing not the theoretical optimum? |
A compromise is made to ensure economic benefit, such as ensuring reaction rate is not too slow |
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If a reversible reaction has more moles of gas on the left of the equation and pressure is increased, what is the effect on equilibrium? |
Equilibrium is moved to the right, favouring the side with the fewest molecules |
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If a reversible reaction has an endothermic forward reaction, what effect will decreasing the temperature have on equilibrium? |
Equilibrium shifts to the right, favouring the exothermic reverse reaction |
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If the equilibrium constant of a reversible reaction is greater than one, what does that tell us? |
The mixture contains mostly products |
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If the equilibrium constant of a reversible reaction is smaller than one, what does that tell us? |
The mixture contains mostly reactants |
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If the equilibrium constant of a reversible reaction is one, what does that tell us? |
The mixture contains roughly equal amounts of reactant and product |
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What is the definition of a functional group? |
A bond, structure, or selection of atoms within a molecule that give it its chemical properties |
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What is a homologous series? |
A family of compounds with similar chemical properties whose successive members differ by a -CH2 group |
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Define empirical formula |
The simplest whole number ratio of elements within a compound |
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Define molecular formula |
A formula showing the number and type of atoms of each element present |
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Define general formula |
The simplest algebraic formula for any member of a homologous series. |
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Define displayed formula |
That which shows the relative positioning of the atoms in a molecule and the bonds between them |
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What is structural formula? |
That which shows the smallest amount of detail necessary to show the arrangement of atoms in a molecule (e.g. CH3CH2CH3) |
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What is skeletal formula? |
A simplified organic formula that doesn't display bonds to hydrogen atoms, only functional groups attached to a carbon skeleton |
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What are structural isomers? |
Compounds with the same molecular formula but different structural fomulae |
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Define the term 'reagent' |
A substance used in the detection or measurement of a component, in preparing a product, or in developing photographs because of its chemical or biological activity |
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Define the term 'reactant' |
A substance consumed through the course of the reaction |
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Define the term 'surroundings' |
Everything not in the system, e.g. the apparatus |
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Define the term 'system' |
The part of the universe being studied; i.e. the reactants, products, catalysts etc. |
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What is percentage yield? |
The actual yield of a reaction compared to the maximum yield possible (theoretical yield) |
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What is meant by 'atom economy'?
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The amount of useful product obtained compared to the total amount of product |
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Why might percentage yield not be 100%? |
Reactants are impure Reversible reactions mean product turned back into reactants Loss of mass during separation Unwanted side reactions occurred |
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What is a saturated hydrocarbon? |
One that has only single C-C bonds |
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What is an unsaturated hydrocarbon? |
One that has at least one double C=C bond (or a triple bond) |
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What are free radicals? |
Species that have one unpaired electron |
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How does a free radical substitution reaction terminate? |
By two radicals colliding to form a non-radical compound |
